Electrically conductive elastic composite yarn, methods for making the same, and articles incorporating the same
An electrically conductive elastic composite yarn comprises an elastic member that is surrounded by at least one conductive covering filament(s). The elastic member has a predetermined relaxed unit length L and a predetermined drafted length of (N×L), where N is a number preferably in the range from about 1.0 to about 8.0. The conductive covering filament has a length that is greater than the drafted length of the elastic member such that substantially all of an elongating stress imposed on the composite yarn is carried by the elastic member. The elastic composite yarn may further include an optional stress-bearing member surrounding the elastic member and the conductive covering filament. The length of the stress-bearing member is less than the length of the conductive covering filament and greater than, or equal to, the drafted length (N×L) of the elastic member, such that a portion of the elongating stress imposed on the composite yarn is carried by the stress-bearing member.
1. A method for forming an electrically conductive elastic composite yarn comprising:
an elastic member having a relaxed length (L);
at least one conductive covering filament surrounding the elastic member, and at least one inelastic synthetic polymer yarn surrounding the elastic member, wherein the conductive covering filament has a length, and the inelastic synthetic polymer yarn has a length that is shorter than the length of the conductive covering filament;
the method comprising the steps of:
drafting the elastic member to a drafted length N×L where N is from about 1.2 to about 8.0;
twisting the conductive covering filament and the inelastic synthetic polymer yarn with the drafted elastic member; and thereafter
allowing the elastic member to relax.
2. The method of claim 1 wherein the electrically conductive elastic composite yarn further comprises a second conductive covering filament surrounding the elastic member,
the method further comprising the steps of:
twisting the second conductive covering filament with the drafted elastic member and the first conductive covering filament; and thereafter
allowing the elastic member to relax.
3. The method of claim 1 wherein the electrically conductive elastic composite yarn further comprises a second inelastic synthetic polymer yarn surrounding the elastic member,
the method further comprising the steps of:
twisting the second inelastic synthetic polymer yarn with the elastic member, the conductive covering filament and the first inelastic synthetic polymer yarn; and thereafter
allowing the elastic member to relax.
4. The method of claim 1 , wherein the elastic member comprises a synthetic bicomponent multifilament textile yarn.
5. The method of claim 1 , wherein the inelastic synthetic polymer yarn is selected from the group consisting of continuous filament yarns, multifilament flat yarns, partially oriented yarns, textured yarns, and bicomponent yarns.